Mobile communication system, core network node, control station, base station, communication method and program

ABSTRACT

A mobile communication system of the present invention is a mobile communication system including a mobile station, base stations each of which forms a cell and transmits MBMS data to the mobile station existing in the cell, control stations each of which controls a base station connected thereto, and further including a core network node that instructs each of the control stations connected thereto with respect to the frequency and timing for transmitting MBMS data in the cell, wherein each of the control stations establishes time synchronization with another control station and instructs the connected base station to set the cell to the frequency designated by the core network node and transmits, to the connected base station, the MBMS data in accordance with the transmission timing designated by the core network node and the mobile station then receives the MBMS data.

This application is a continuation of U.S. application Ser. No.14/795,200, filed Jul. 9, 2015, which is a continuation of U.S.application Ser. No. 13/122,476, filed Apr. 4, 2011, now U.S. Pat. No.9,113,440, which is a National Stage of International Application No.PCT/JP2009/065717, filed Sep. 9, 2009, claiming priority based on JPApplication No. 2008-281441, filed Oct. 31, 2008, the contents of all ofwhich are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a mobile communication system, a corenetwork node, a control station, a base station, a communication methodand a program.

BACKGROUND ART

3GPP (3rd Generation Partnership Projects) defines a service called“MBMS” (Multimedia Broadcast Multicast Service) (Non Patent Literature1˜7).

MBMS is a service that simultaneously transmits, by broadcasting ormulticasting, multimedia data (hereinafter referred to as “MBMS data”)such as video and music to a plurality of UEs (User Equipment: mobilestation).

Furthermore, 3GPP defines a scheme called “MBSFN (Multicast BroadcastSingle Frequency Network)” as the scheme for providing MBMS.

MBSFN is a scheme for transmitting the same MBMS data to UEs in aplurality of cells formed by a plurality of Nodes B (base stations)using the same frequency and at the same timing.

Thus, when viewed from UEs, a plurality of cells can be regarded as onelarge communication area. This communication area is called “MBSFNcluster” and the UEs can receive MBMS data with a large gain under thecontrol of the MBSFN cluster.

The plurality of cells that form the MBSFN cluster use not only the samefrequency but also the same scrambling code, channelisation code andslot format or the like. In the present specification, the frequency,scrambling code, channelisation code and slot format are genericallycalled “radio resources.” To be more specific, these radio resources areused for S-CCPCH (Secondary Common Control Physical Channel) which is acommon physical channel used to wirelessly transmit MBMS data from aNode B to a UE in each cell.

FIG. 1 illustrates an example of configuration of a mobile communicationsystem of W-CDMA (Wideband-Code Division Multiple Access) that providesMBMS using an MBSFN (Non Patent Literature 1).

As shown in FIG. 1, the related mobile communication system includesBM-SC (Broadcast Multicast-Service Center) 100, GGSN (Gateway GPRSSupport Node, GPRS=General Packet Radio Service) 200, SGSN (Serving GPRSSupport Node) 300, RNC (Radio Network Controller: control station) 400,Node B (NB) 500 and UE 800.

FIG. 1 shows two RNCs 400-1 and 400-2 as RNC 400.

Furthermore, though not shown in the figure, BM-SC 100, GGSN 200 andSGSN 300 are arranged in a CN (Core Network) and RNC 400 and Node B500are arranged in RAN (Radio Access Network) 450 which will be describedlater. RAN 450 generally has a configuration in which a plurality ofNodes B 500 are connected to one RNC 400.

BM-SC 100 is a node provided with a function of authenticating a user ofUE 800 to which MBMS data is transmitted, a function of managing MBMSdata and a function of scheduling distribution of MBMS data or the like.Details of these operations are defined in 3GPP and are commonly known,and therefore descriptions thereof will be omitted.

GGSN 200 is a gateway node provided with a function of transferring anIP (Internet Protocol) packet (message and MBMS data integrated into anIP packet) sent from BM-SC 100 to SGSN 300 and a function oftransferring the IP packet sent from SGSN 300 to BM-SC 100 or the like.Since details of these operations are defined in 3GPP and are commonlyknown, descriptions thereof will be omitted.

SGSN 300 is a node provided with a function of routing/transferring anIP packet, a function of performing mobility management and sessionmanagement necessary for mobile communication or the like. Since detailsof these operations are defined in 3GPP and are commonly known,descriptions thereof will be omitted.

RNCs 400-1 and 400-2 are nodes provided with a function of controllingRAN 450. For example, RNCs 400-1 and 400-2 determine radio resources ofS-CCPCH in cells 600 under their control, instruct Node B 500 to set theS-CCPCH, determine transmission timing for transmitting MBMS data incell 600 under their control and transmit MBMS data to each Node B 500in synchronization with the transmission timing. Since details of theseoperations are defined in 3GPP and are commonly known, descriptionsthereof will be omitted. Assume that “under control” in the presentspecification refers to subordinate nodes connected to the own node,cells formed by the subordinate nodes, MBSFN clusters or the like.

Thus, RNCs 400-1 and 400-2 independently determine radio resources andtransmission timing in cells 600 under their control.

Thus, MBSFN cluster 700-1 under the control of RNC 400-1 and MBSFNcluster 700-2 under the control of RNC 400-2 are formed respectively.

Node B 500 is a node provided with a function of setting radio resourcesin an S-CCPCH based on instructions from RNCs 400-1 and 400-2 and afunction of converting MBMS data sent from RNCs 400-1 and 400-2 to radiodata and transmitting the radio data to UE 800 in cell 600 through theS-CCPCH. Since details of these operations are defined in 3GPP and arecommonly known, descriptions thereof will be omitted.

Here, with reference to FIG. 2, gains of UE 800 when MBSFN is used willbe described in comparison with gains when MBSFN is not used. In FIG. 2,(a) shows frequency utilization efficiency of UE 800 when MBSFN is used,disclosed in Table 7 of Non Patent Literature 2 and (b) shows frequencyutilization efficiency of UE 800 when MBSFN is not used, disclosed inTable 8 of Non Patent Literature 2.

First, a case will be described as an example where UE 800 is a Type-3receiver and has a configuration of combining signals received throughthree radio links (receiver capable of equalizing 3RLs, RL=Radio Link).In this case, the frequency utilization efficiency is 0.602 [b/s/Hz]when MBSFN is used, whereas the frequency utilization efficiency is aslow as 0.4736 [b/s/Hz] when MBSFN is not used. On the other hand, whenthere are seven radio links, the frequency utilization efficiency is1.075 [b/s/Hz] when MBSFN is used, which is significantly different from0.4736 [b/s/Hz] when MBSFN is not used.

It is obvious from this result that gains of UE 800 are very small whenMBSFN is not used.

CITATION LIST Non Patent Literature

Non Patent Literature 1: 3GPP TS 23.246

Non Patent Literature 2: 3GPP TS 25.905

Non Patent Literature 3: 3GPP TS 29.061

Non Patent Literature 4: 3GPP TS 29.060

Non Patent Literature 5: 3GPP TS 25.413

Non Patent Literature 6: 3GPP TS 25.402

Non Patent Literature 7: 3GPP TS 24.008

SUMMARY OF INVENTION Technical Problem

However, in different RNCs of the related mobile communication system,there is no means for unifying S-CCPCH radio resources in cells undertheir control and MBMS data transmission timing, and therefore each RNCindependently determines radio resources in a cell under its control andtransmission timing.

For this reason, one MBSFN cluster can only be formed for each RNC andcannot be formed extending over different RNCs. That is, one MBSFNcluster cannot be formed between cells under the control of differentRNCs.

Therefore, in the vicinity of a boundary of cells of Nodes B connectedto different RNCs, since a UE is located on a boundary of MBSFNclusters, there is a problem in which the effect of MBSFN of receivingMBMS data with large gains is lessened.

Moreover, assuming the number of Nodes B connected to one RNC isconstant, a communication area where there are more UEs requires moreNodes B. Thus, the communication area covered by one RNC shrinks insize. This means that there are more boundaries of communication areasof RNCs in areas where there are more UEs.

Therefore, even when one MBSFN cluster is formed for each RNC, moreboundaries of MBSFN clusters are formed in areas where there are moreUEs, and there is a problem in which the effect of MBSFN is lessened.

It is therefore an object of the present invention to provide a mobilecommunication system, a core network node, a control station, a basestation, a communication method and a program that, by expanding therange of an MBSFN cluster, reduces the number of boundaries of MBSFNclusters, and thereby solves the above described problems.

Solution to Problem

A first mobile communication system of the present invention is a mobilecommunication system including

-   -   a mobile station,    -   base stations each of which forms a cell and transmits MBMS data        to the mobile station in the cell and    -   control stations each of which controls a base station connected        thereto,    -   and further including    -   a core network node that instructs each of the control stations        connected thereto with respect to the frequency and timing for        transmitting MBMS data in the cell,    -   wherein each of the control stations    -   establishes time synchronization with another control station,    -   instructs the connected base station to set the cell to the        frequency designated by the core network node,    -   transmits, to the connected base station, the MBMS data in        accordance with the transmission timing designated by the core        network node and    -   the mobile station receives the MBMS data.

A second mobile communication system of the present invention is amobile communication system including

-   -   a mobile station and    -   base stations each of which forms a cell and transmits MBMS data        to the mobile station in the cell,    -   and further including    -   a core network node that instructs each of the control stations        connected thereto with respect to the frequency and timing for        transmitting MBMS data in the cell,    -   wherein the base station    -   establishes time synchronization with another base station,    -   sets the cell to the frequency designated by the core network        node,    -   transmits the MBMS data to the mobile station at transmission        timing designated by the core network node and    -   the mobile station receives the MBMS data.

A core network node of the present invention is a core network nodeconnected to base stations each of which forms a cell and transmits MBMSdata to a mobile station in the cell, including

-   -   a communication unit that instructs a base station connected        thereto or a control station connected to the base station with        respect to the frequency and timing for transmitting the MBMS        data in the cell.

A control station of the present invention is a control stationconnected to base stations each of which forms a cell and transmits MBMSdata to a mobile station in the cell, including

-   -   a time synchronization unit that establishes time        synchronization with another control station and    -   a communication unit that receives an instruction from a higher        core network node with respect to the frequency and timing for        transmitting the MBMS data in the cell, instructs a base station        connected thereto to set the cell to the frequency designated by        the core network node and transmits the MBMS data in accordance        with the transmission timing designated by the core network        node.

A base station of the present invention is a base station that forms acell and transmits MBMS data to a mobile station in the cell, including

-   -   a time synchronization unit that establishes time        synchronization with another base station    -   a communication unit that receives an instruction from a higher        core network node with respect to the frequency and timing for        transmitting the MBMS data in the cell and transmits the MBMS        data to the mobile station in accordance with the transmission        timing designated by the core network node and    -   a control unit that sets the cell to the frequency designated by        the core network node.

A first communication method of the present invention is a communicationmethod by a mobile communication system made up of a mobile station,base stations each of which forms a cell and transmits MBMS data to themobile station in the cell, control stations each of which controls abase station connected thereto and a core network node connected to thecontrol stations, including the steps of

-   -   the core network node instructing a control station connected        thereto with respect to the frequency and timing for        transmitting the MBMS data in the cell,    -   the control station establishing time synchronization with        another control station,    -   the control station instructing the connected base station to        set the cell to the frequency designated by the core network        node,    -   the control station transmitting, to the connected base station,        the MBMS data in accordance with the transmission timing        designated by the core network node and the mobile station        receiving the MBMS data.

A second communication method of the present invention is acommunication method by a mobile communication system made up of amobile station, base stations each of which forms a cell and transmitsMBMS data to the mobile station in the cell and a core network nodeconnected to the base stations, including the steps of

-   -   the core network node instructing a base station connected        thereto with respect to the frequency and timing for        transmitting the MBMS data in the cell,    -   the base station establishing time synchronization with another        base station,    -   the base station setting the cell to the frequency designated by        the core network node,    -   the base station transmitting the MBMS data to the mobile        station in accordance with the transmission timing designated by        the core network node and    -   the mobile station receiving the MBMS data.

A third communication method of the present invention is a communicationmethod by a core network node connected to base stations each of whichforms a cell and transmits MBMS data to a mobile station in the cell,including the steps of

-   -   instructing a base station connected thereto or a control        station connected to the base station with respect to the        frequency and timing for transmitting the MBMS data in the cell.

A fourth communication method of the present invention is acommunication method by a control station connected to base stationseach of which forms a cell and transmits MBMS data to a mobile stationin the cell, including the steps of

-   -   establishing time synchronization with another control station,    -   receiving an instruction with respect to the frequency and        timing for transmitting the MBMS data in the cell from a higher        core network node,    -   instructing a base station connected thereto to set the cell to        the frequency designated by the core network node and    -   transmitting the MBMS data to the connected base station in        accordance with the transmission timing designated by the core        network node.

A fifth communication method of the present invention is a communicationmethod by a base station which forms a cell and transmits MBMS data to amobile station in the cell, including the steps of

-   -   establishing time synchronization with another base station,    -   receiving an instruction with respect to the frequency and        timing for transmitting the MBMS data in the cell from a higher        core network node,    -   transmitting the MBMS data to a mobile station in accordance        with the transmission timing designated by the core network node        and    -   setting the cell to the frequency designated by the core network        node.

A first program of the present invention causes a core network nodeconnected to base stations each of which forms a cell and transmits MBMSdata to a mobile station in the cell to execute the processes of

-   -   instructing a base station connected thereto or a control        station connected to the base station with respect to the        frequency and timing for transmitting the MBMS data in the cell.

A second program of the present invention causes a control stationconnected to base stations each of which forms a cell and transmits MBMSdata to a mobile station in the cell to execute the processes of

-   -   establishing time synchronization with another control station,    -   receiving an instruction with respect to the frequency and        timing for transmitting the MBMS data in the cell from a higher        core network node,    -   instructing a base station connected thereto to set the cell to        the frequency designated by the core network node and    -   transmitting the MBMS data to the connected base station in        accordance with the transmission timing designated by the core        network node.

A third program of the present invention causes a base station whichforms a cell and transmits MBMS data to a mobile station in the cell toexecute the processes of

-   -   establishing time synchronization with another base station,    -   receiving an instruction with respect to the frequency and        timing for transmitting the MBMS data in the cell from a higher        core network node,    -   transmitting the MBMS data to the mobile station in accordance        with the transmission timing designated by the core network node        and    -   setting the cell to the frequency designated by the core network        node.

Advantageous Effects of Invention

According to the present invention, it is possible to transmit the sameMBMS data using the same frequency and at the same transmission timingin all cells under the control of a core network node.

Therefore, the present invention provides an advantage of being able toexpand a range of communication area made up of a plurality of cells inwhich the same MBMS data are transmitted using the same frequency and atthe same transmission timing.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example of a configuration ofa related mobile communication system;

FIG. 2 is a diagram illustrating gains of a UE when MBSFN is used;

FIG. 3 is a diagram illustrating an example of a configuration of amobile communication system of the present invention;

FIG. 4 is a block diagram illustrating an example of a configuration ofthe BM-SC, GGSN, SGSN and RNC shown in FIG. 3;

FIG. 5 is a C-plane sequence chart illustrating an example of operationat the start of a session of MBMS in the mobile communication system ofthe present invention;

FIG. 6 is a diagram illustrating a C-plane protocol stack used totransmit/receive the C-plane message shown in FIG. 5;

FIG. 7 is a diagram illustrating an example of a Session Start Requestmessage transmitted from the BM-SC to GGSN in step S10 shown in FIG. 5;

FIG. 8 is a diagram illustrating an example of an MBMS Session StartRequest message transmitted from the GGSN to SGSN in step S20 shown inFIG. 5;

FIG. 9 is a diagram illustrating an example of an MBMS Session StartRequest message transmitted from the SGSN to RNC in step S30 shown inFIG. 5;

FIG. 10 is a block diagram illustrating another example of theconfiguration of the BM-SC, GGSN, SGSN and RNC shown in FIG. 3;

FIG. 11 is a diagram illustrating another example of the Session StartRequest message transmitted from the BM-SC to GGSN in step S10 shown inFIG. 5;

FIG. 12 is a diagram illustrating another example of the MBMS SessionStart Request message transmitted from the GGSN to SGSN in step S20shown in FIG. 5;

FIG. 13 is a diagram illustrating another example of the MBMS SessionStart Request message transmitted from the SGSN to RNC in step S30 shownin FIG. 5;

FIG. 14 is a diagram illustrating an example of a database stored in thestorage unit of the RNC shown in FIG. 10;

FIG. 15 is a diagram illustrating a further example of the Session StartRequest message transmitted from the BM-SC to GGSN in step S10 shown inFIG. 5;

FIG. 16 is a diagram illustrating a configuration of TMGI shown in FIG.15;

FIG. 17 is a diagram illustrating an example of the MBMS Service IDshown in FIG. 16 broken down into three parts;

FIG. 18 is a diagram illustrating another example of the database storedin the storage unit of the RNC shown in FIG. 10;

FIG. 19 is a block diagram illustrating another example of theconfiguration of the mobile communication system of the presentinvention;

FIG. 20 is a block diagram illustrating an example of the configurationof the BM-SC, GGSN, SGSN and RNC shown in FIG. 19;

FIG. 21 is a block diagram illustrating a further example of theconfiguration of the mobile communication system of the presentinvention;

FIG. 22 is a block diagram illustrating an example of the configurationof the BM-SC and Node B shown in FIG. 21;

FIG. 23 is a block diagram illustrating a still further example of theconfiguration of the mobile communication system of the presentinvention; and

FIG. 24 is a block diagram illustrating an example of the configurationof the BM-SC and Node B shown in FIG. 23.

DESCRIPTION OF EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will bedescribed with reference to the accompanying drawings.

(1) First Exemplary Embodiment (1-1) Configuration of First ExemplaryEmbodiment

As shown in FIG. 3, although an overall configuration of the mobilecommunication system of the present exemplary embodiment is the same asthat in FIG. 1, functions are added to BM-SC 100, GGSN 200, SGSN 300,and RNCs 400-1 and 400-2.

Thus, configurations of BM-SC 100, GGSN 200, SGSN 300, and RNCs 400-1and 400-2 will be described with reference to FIG. 4.

As shown in FIG. 4, BM-SC 100 serves as a core network node to instructRNCs 400-1 and 400-2 with respect to MBSFN information that is necessaryto form MBSFN cluster 700 under the control of RNCs 400-1 and 400-2 viaGGSN 200 and SGSN 300 and includes control unit 101 and communicationunit 102.

Control unit 101 generates a message to be transmitted to GGSN 200. Forexample, in the present exemplary embodiment, control unit 101generates, as MBSFN information, a message including set values of radioresources of S-CCPCH (frequency, scrambling code, channelisation code,slot format) in cell 600 under control thereof and set values oftransmission timing of MBMS data (e.g., transmission time in hour/minuteunits such as x hours y minutes). Although the set values of the radioresources and transmission timing may be manually set by a systemadministrator in, for example, BM-SC 100, this is not exclusive.

In addition to the aforementioned operations, control unit 101 controlsBM-SC 100 as a whole and performs various types of operation, forexample, user authentication described in FIG. 1, MBMS data managementand delivery scheduling.

Communication unit 102 transmits/receives messages and MBMS data to/fromGGSN 200. For example, in the present exemplary embodiment,communication unit 102 transmits a message including set values of radioresources and transmission timing generated by control unit 101 to GGSN200.

GGSN 200 includes control unit 201 and communication unit 202.

Control unit 201 generates messages to be transmitted to BM-SC 100 andSGSN 300. For example, in the present exemplary embodiment, control unit201 generates messages including set values of radio resources andtransmission timing reported from BM-SC 100.

In addition to the aforementioned operation, control unit 201 controlsGGSN 200 as a whole and performs various types of operation.

Communication unit 202 transmits/receives messages and MBMS data to/fromBM-SC 100 and SGSN 300. For example, in the present exemplaryembodiment, communication unit 202 receives a message including setvalues of radio resources and transmission timing from BM-SC 100 andtransmits a message including set values of radio resources andtransmission timing generated by control unit 201 to SGSN 300.

SGSN 300 includes control unit 301 and communication unit 302.

Control unit 301 generates a message to be transmitted to GGSN 200, andRNCs 400-1 and 400-2. For example, in the present exemplary embodiment,control unit 301 generates a message including set values of radioresources and transmission timing reported from GGSN 200.

In addition to the aforementioned operation, control unit 301 controlsSGSN 300 as a whole and performs various types of operation such asrouting, mobility management and session management described in FIG. 1.

Communication unit 302 transmits/receives messages and MBMS data to/fromGGSN 200, and RNCs 400-1 and 400-2. For example, in the presentexemplary embodiment, communication unit 302 receives a messageincluding set values of radio resources and transmission timing fromGGSN 200 and transmits a message including set values of radio resourcesand transmission timing generated by control unit 301 to RNC 400-1. Thismessage is also transmitted to RNC 400-2.

RNC 400-1 includes time synchronization unit 401, control unit 402 andcommunication unit 403. RNC 400-2 also has a configuration similar tothat of RNC 400-1.

Time synchronization unit 401 receives time information of UTC(Coordinated Universal Time) from GPS (Global Positioning System)satellite 900 and synchronizes time of RNC 400-1 with UTC. Since themethod of time synchronization with UTC by GPS is commonly known,descriptions thereof will be omitted.

In this case, RNC 400-2 also establishes time synchronization with UTC.

This makes it possible to establish time synchronization between RNCs400-1 and 400-2.

The method of establishing time synchronization between RNCs 400-1 and400-2 is not limited to the aforementioned method using GPS, but thefollowing methods defined in 3GPP can also be used.

-   -   3GPP synchronization method in UTRAN (UMTS Terrestrial Radio        Access Network, UMTS=Universal Mobile Telecommunications System)        (3GPP synchronization in UTRAN)    -   Method using NTP (Network Time Protocol)    -   Method using IP multicast distribution (Relying on IP multicast        distribution)    -   Method defined in IEEE (Institute of Electrical and Electronic        Engineers) 1588 Control unit 402 generates messages and        instructions to be transmitted to SGSN 300 and Node B 500. For        example, in the present exemplary embodiment, control unit 402        generates an instruction for setting the set values of radio        resources reported from SGSN 300 in S-CCPCH.

Furthermore, control unit 402 can recognize a timing difference betweenRNC 400-1 and each Node B 500 under control thereof, using a nodesynchronization procedure described in Non Patent Literature 6. Thisallows control unit 402 to recognize at which timing MBMS data should betransmitted to each Node B 500 under control thereof so that MBMS datais transmitted to all cells 600 under control thereof at the sametransmission timing. Thus, control unit 402 schedules timing of MBMSdata to be transmitted to each Node B 500 under control thereof so thatMBMS data is transmitted to all cells 600 under control thereof at thetransmission timing reported from SGSN 300.

In addition to the aforementioned operation, control unit 402 controlsRNC 400-1 as a whole and performs various types of operation.

Communication unit 403 transmits/receives messages, MBMS data andinstructions to/from SGSN 300 and Node B 500. For example, in thepresent exemplary embodiment, communication unit 403 receives messagesincluding set values of radio resources and transmission timing fromSGSN 300 and transmits, to all Nodes B 500 under the control of RNC400-1, an instruction for setting the radio resources generated bycontrol unit 402 and reported from SGSN 300 in S-CCPCH.

In this case, RNC 400-2 likewise transmits, to all Nodes B 500 under thecontrol of RNC 400-2, an instruction for setting the radio resourcesreported from SGSN 300 in S-CCPCH.

This allows all cells 600 under the control of RNCs 400-1 and 400-2 touse the same radio resources for S-CCPCH.

Furthermore, communication unit 403 transmits MBMS data to each Node B500 under the control of RNC 400-1 at timing scheduled by control unit402. This allows transmission timing of MBMS data in all cells 600 undercontrol thereof to match the transmission timing reported from SGSN 300.

In this case, RNC 400-2 likewise performs scheduling so thattransmission timing of MBMS data in all cells 600 under control thereofmatches the transmission timing reported from SGSN 300.

Furthermore, time synchronization is established between RNCs 400-1 and400-2.

This allows the same MBMS data to be transmitted at the sametransmission timing in all cells 600 under the control of RNCs 400-1 and400-2.

As described so far, all cells 600 under the control of RNCs 400-1 and400-2 can transmit the same MBMS data using the same frequency and atthe same transmission timing, making it possible to form wide-rangeMBSFN cluster 700 extending over RNCs 400-1 and 400-2.

(1-2) Operation of First Exemplary Embodiment

Next, operation of the mobile communication system of the presentexemplary embodiment at the start of MBMS, that is, at the start of asession, will be described according to a C-plane (Control Plane)sequence chart shown in FIG. 5. The “C-plane” refers to a control planeand shows a protocol for signals used for control in a network.

In order to transmit/receive C-plane messages shown in FIG. 5, thepresent exemplary embodiment uses a C-plane protocol stack shown in FIG.6 without changing it. Since this protocol stack is defined in 3GPP,detailed descriptions thereof will be omitted.

As shown in FIG. 5, communication unit 102 of BM-SC 100 transmits aSession Start Request message to GGSN 200 at the start of a session ofMBMS in step S10. Details of the Session Start Request message aredescribed in Non Patent Literature 3.

In the present exemplary embodiment, control unit 101 of BM-SC 100 newlyadds parameters of MBSFN-Frequency 12, MBSFN-Scrambling-Code 13,MBSFN-Channelisation-Code 14, MBSFN-Slot-Format 15 and MBSFN-Tx-Timing16 in the Session Start Request message in step S10 as shown in FIG. 7.Each Node B 500 uses the set values of frequency, scrambling code,channelization code and slot format in these parameters to set S-CCPCH,and each Node B 500 transmits MBMS data with a set value of thetransmission timing.

Next, communication unit 202 of GGSN 200 returns a Session StartResponse message which is a response message to the Session StartRequest message to BM-SC 100 in step S11.

The Session Start Request message and Session Start Response messagetransmitted and received between BM-SC 100 and GGSN 200 are transmittedthrough Gmb interface 151 shown in FIG. 6 using Diameter Protocol 150.Details of Diameter Protocol 150 are described in Non Patent Literature3.

Next, communication unit 202 of GGSN 200 transmits an MBMS Session StartRequest message to SGSN 300 in step S20.

In the present exemplary embodiment, control unit 201 of GGSN 200 newlyadds parameters corresponding to MBSFN-Frequency 12,MBSFN-Scrambling-Code 13, MBSFN-Channelisation-Code 14,MBSFN-Slot-Format 15 and MBSFN-Tx-Timing 16, included in the aboveSession Start Request message as shown in FIG. 8, in the MBMS SessionStart Request message in step S20. Suppose the number of bits of each ofthese parameters is the same as the number of bits of the parametersincluded in the Session Start Request message.

Next, communication unit 302 of SGSN 300 returns an MBMS Session StartResponse message which is a response message to the MBMS Session StartRequest message to GGSN 200 in step S21.

The MBMS Session Start Request message and MBMS Session Start Responsemessage transmitted and received between GGSN 200 and SGSN 300 aretransmitted through Gn interface 251 shown in FIG. 6, using GTP-CProtocol 250. Details of GTP-C Protocol 250 are described in Non PatentLiterature 4.

Next, communication unit 302 of SGSN 300 transmits an MBMS Session StartRequest message to RNCs 400-1 and 400-2 in step S30. Details of the MBMSSession Start Request message are described in Non Patent Literature 5.

In the present exemplary embodiment, control unit 301 of SGSN 300 adds agroup called “MBSFN Information” as shown in FIG. 9 in the MBMS SessionStart Request message in step S30 and includes therein MBSFN-Frequency,MBSFN-Scrambling-Code, MBSFN-Channelisation-Code, MBSFN-Slot-Format andMBSFN-Tx-Timing as IE (Information Element) to be new parameters.

Control unit 402 of RNC 400-1 can recognize an S-CCPCH frequency of cell600 under control thereof from MBSFN-Frequency, can recognize scramblingcode from MBSFN-Scrambling-Code, can recognize channelisation code fromMBSFN-Channelisation-Code, can recognize slot format fromMBSFN-Slot-Format and can recognize timing for transmitting the MBMSdata from MBSFN-Tx-Timing respectively designated by BM-SC 100. RNC400-2 can likewise recognize the same.

Next, communication unit 403 of RNC 400-1 returns an MBMS Session StartResponse message which is a response message to the MBMS Session StartRequest message to SGSN 300 in step S31. RNC 400-2 likewise returns anMBMS Session Start Response message.

The MBMS Session Start Request message and MBMS Session Start Responsemessage transmitted and received between SGSN 300, and RNC 400-1 and400-2 are transmitted through Iu-PS interface 351 shown in FIG. 6, usingRANAP Protocol 350. Details of RANAP Protocol 350 are described in NonPatent Literature 5.

In step S40, a RAN resource setup procedure is executed between RNC400-1 and Node B 500 under control thereof.

In the RAN resource setup procedure, communication unit 403 of RNC 400-1transmits, to all Node Bs 500 under control thereof, an instruction forsetting the set values of frequency, scrambling code, channelisationcode and slot format designated by BM-SC 100 in S-CCPCH. Upon receivingthis, all Nodes B 500 under the control of RNC 400-1 set these radioresources in S-CCPCH.

Likewise, all Nodes B 500 under the control of RNC 400-2 set the setvalues of radio resources designated by BM-SC 100 in S-CCPCH.

This allows all cells 600 under the control of RNCs 400-1 and 400-2 touse the same radio resources for S-CCPCH.

Furthermore, time synchronization unit 401 of RNC 400-1 receives timeinformation of UTC from GPS satellite 900 and synchronizes time of RNC400-1 with UTC.

Likewise, time of RNC 400-2 is also synchronized with UTC.

This makes it possible to establish time synchronization between RNCs400-1 and 400-2.

Furthermore, control unit 402 of RNC 400-1 performs scheduling so thattransmission timing of MBMS data in all cells 600 under control thereofmatches the set values of transmission timing designated by BM-SC 100.

In RNC 400-2, transmission timing of MBMS data in all cells 600 undercontrol thereof is likewise made to match the set values of transmissiontiming designated by BM-SC 100.

This allows all cells 600 under the control of RNCs 400-1 and 400-2 totransmit the same MBMS data at the same transmission timing.

As described above, in the present exemplary embodiment, all cells 600under the control of RNCs 400-1 and 400-2 can transmit the same MBMSdata at the same transmission timing using the same frequency, and canthereby form wide-range MBSFN cluster 700 extending over RNCs 400-1 and400-2.

Therefore, UE 800 can obtain the effect of MBSFN even when located at aposition on boundary between the communication area of RNC 400-1 and thecommunication area of RNC 400-2.

Furthermore, UE 800 can continuously receive MBMS data without beingaware of differences in RNC, differences in Node B and differences incell.

(2) Second Exemplary Embodiment (2-1) Configuration of Second ExemplaryEmbodiment

The overall configuration of a mobile communication system of thepresent exemplary embodiment is similar to that in FIG. 3.

In the present exemplary embodiment, BM-SC 100 reports not set values ofradio resources themselves of the MBSFN information as in the case ofthe aforementioned first exemplary embodiment but MBSFN-Indicator whichis an identifier indicating a combination of these set values as theinformation of set values of radio resources in each cell 600.

Thus, as shown in FIG. 10, RNC 400-1 adopts a configuration with storageunit 404 that stores a table which associates the above describedMBSFN-Indicator with a combination of set values of radio resourcesadded to the configuration in FIG. 4. The same applies to RNC 400-2,too.

(2-2) Operation of Second Exemplary Embodiment

Since the C-plane sequence chart at the start of a session of MBMS ofthe mobile communication system of the present exemplary embodiment issimilar to that in FIG. 5, descriptions thereof will be omitted.

However, in the present exemplary embodiment, control unit 101 of BM-SC100 newly adds parameters of MBSFN-Tx-Timing 16 and MBSFN-Indicator 17as shown in FIG. 11 in the Session Start Request message in step S10.

MBSFN-Indicator 17 becomes an identifier for instructing RNCs 400-1 and400-2 with respect to use or non-use of MBSFN or a combination of setvalues of radio resources when MBSFN is used. In the present exemplaryembodiment, assume that MBSFN-Indicator 17 is a 4-bit parameter.

Furthermore, in the present exemplary embodiment, control unit 201 ofGGSN 200 newly adds parameters corresponding to MBSFN-Tx-Timing 16 andMBSFN-Indicator 17 included in the above described Session Start Requestmessage as shown in FIG. 12 in the MBMS Session Start Request message instep S20.

Furthermore, in the present exemplary embodiment, control unit 301 ofSGSN 300 includes MBSFN-Tx-Timing and MBSFN-Indicator as a new IE inMBSFN Information as shown in FIG. 13 in the MBMS Session Start Requestmessage in step S30.

Furthermore, in the present exemplary embodiment, storage unit 404 ofRNC 400-1 stores a database as shown in FIG. 14 beforehand.

Upon receiving a MBMS Session Start Request message in step S30, controlunit 402 of RNC 400-1 refers to the database in FIG. 14 using the valueof MBSFN-Indicator included therein as an argument.

In the example in FIG. 14, when the value of MBSFN-Indicator is 0,control unit 402 of RNC 400-1 determines not to use MBSFN and performsconventional processing of MBMS. In this case, the value ofMBSFN-Tx-Timing is ignored.

On the other hand, when the value of MBSFN-Indicator is other than 0,control unit 402 of RNC 400-1 determines to use MBSFN, selects thecombination of the set values of frequency, scrambling code,channelisation code and slot format corresponding to the value,generates an instruction for setting these set values of radio resourcesin S-CCPCH and transmits the instruction from communication unit 403 toNode B 500 under control thereof.

Furthermore, control unit 402 of RNC 400-1 recognizes the set value oftransmission timing of MBMS data from MBSFN-Tx-Timing as in the case ofthe first exemplary embodiment, performs scheduling and thereby matchesthe transmission timing of MBMS data among all cells 600 under controlthereof.

In RNC 400-2, frequency, scrambling code, channelisation code and slotformat are likewise set in S-CCPCH in cell 600 under control thereof andthe transmission timing of MBMS data is matched.

As described above, in the present exemplary embodiment, BM-SC 100 caninstruct RNCs 400-1 and 400-2 with respect to use or non-use of MBSFNand a combination of set values of radio resources when MBSFN is usedusing MBSFN-Indicator.

Thus, the present exemplary embodiment can also form wide-range MBSFNcluster 700 extending over RNCs 400-1 and 400-2.

(3) Third Exemplary Embodiment

(3-1) Configuration of third exemplary embodiment

An overall configuration of a mobile communication system of the presentexemplary embodiment is similar to that in FIG. 3.

Furthermore, configurations of BM-SC 100, GGSN 200, SGSN 300, and RNCs400-1 and 400-2 of the present exemplary embodiment are similar to thosein FIG. 10.

(3-2) Operation of Third Exemplary Embodiment

Since a C-plane sequence chart of the mobile communication system of thepresent exemplary embodiment at the start of a session of MBMS issimilar to that in FIG. 5, descriptions thereof will be omitted.

However, the present exemplary embodiment, when transmitting MBSFNinformation to RNCs 400-1 and 400-2, BM-SC 100, GGSN 200 and SGSN 300,do not newly add parameters to messages but use parameters of TMGI(Temporary Mobile Group Identity) that is defined based on thesemessages.

Here, a case with the Session Start Request message in step S10 will bedescribed as an example.

As shown in FIG. 15, TMGI 18 is originally defined in the Session StartRequest message. TMGI 18 has a configuration as shown in FIG. 16.Details of the configuration of TMGI 18 are described in Non PatentLiterature 7.

The present exemplary embodiment focuses attention on MBMS Service ID170 included in TMGI 18.

MBMS Service ID 170 is originally made up of three octets, that is, 24bits.

The present exemplary embodiment breaks down the 24 bits of MBMS ServiceID 170 into three parts as shown in FIG. 17. Part 1 corresponds to onebit, specifically the 24th bit, part 2 corresponds to seven bits,specifically the 17th to 23rd bits and part 3 corresponds to 16 bits,specifically the first to 16th bits. Parts 1 to 3 are assigned thefollowing roles respectively.

Part 1:Use or non-use of MBSFN. “1” in this bit means use of MBSFN and“0” means non-use.

Part 2: Parameter of MBSFN. This defines radio resources of S-CCPCH andtiming for transmitting the MBMS data in cell 600 under the control ofRNCs 400-1 and 400-2.

Part 3: Service ID. This indicates Service ID.

The method of categorization of the aforementioned parts is an exampleand is not limited to this. There can be empty bits among the 24 bits ofMBMS Service ID 170.

Furthermore, TMGI's defined in the MBMS Session Start Request messagesin steps S20 and S30 are also assigned the above described roles.

Storage unit 404 of RNC 400-1 stores a database as shown in FIG. 18beforehand.

Upon receiving the MBMS Session Start Request message in step S30,control unit 402 of RNC 400-1 determines to use MBSFN when “1” is set inthe bit of part 1 of TMGI included in this and refers to the database inFIG. 18 using the values of seven bits of part 2 as an argument.

In the database in FIG. 14 used in the above described second exemplaryembodiment, since the argument has 4 bits, only four set values offrequency, scrambling code, channelisation code and slot format can bedefined.

Thus, in the second exemplary embodiment, set values of transmissiontiming of MBMS data are defined using different parameters and reportedfrom BM-SC 100 to RNCs 400-1 and 400-2.

By contrast, since the argument in the database in FIG. 18 used in thepresent exemplary embodiment has 7 bits, the set value of transmissiontiming is also defined in the database.

For example, in the database in FIG. 18, the transmission timing isdefinable only in minute units of transmission time. When the currenttime is 16:55 and “0” is set in the transmission timing, control unit402 of RNC 400-1 performs scheduling such that MBMS data is transmittedfrom Node B 500 at 17:00 which corresponds to the next time “0” minutesare set.

On the other hand, control unit 402 of RNC 400-1 determines not to useMBSFN when “0” is set in the bit of part 1 of TMGI included in the MBMSSession Start Request message in step S30, does not handle the values ofpart 2 and handles the values of part 3 as MBMS Service ID.

Likewise, RNC 400-2 can also recognize radio resources and transmissiontiming in cells 600 under control thereof from parameters of TMGI.

As described above, in the present exemplary embodiment, BM-SC 100 canalso use TMGI to instruct RNCs 400-1 and 400-2 with respect to use ornon-use of MBSFN, and a combination of set values of radio resources andtransmission timing when MBSFN is used.

Thus, the present exemplary embodiment can also form wide-range MBSFNcluster 700 extending over RNCs 400-1 and 400-2.

(4) Fourth Exemplary Embodiment (4-1) Configuration of Fourth ExemplaryEmbodiment

An overall configuration of a mobile communication system of the presentexemplary embodiment is similar to that in FIG. 3.

Furthermore, configurations of BM-SC 100, GGSN 200, SGSN 300, and RNCs400-1 and 400-2 of the present exemplary embodiment are also similar tothose in FIG. 4 or FIG. 10.

(4-2) Operation of Fourth Exemplary Embodiment

Since a C-plane sequence chart of the mobile communication system of thepresent exemplary embodiment at the start of a session of MBMS issimilar to that in FIG. 5, descriptions thereof will be omitted.

However, in the present exemplary embodiment, BM-SC 100 reports only theinformation indicating use or non-use of MBSFN of the MBSFN informationto RNCs 400-1 and 400-2 through the Session Start Request message instep S10. As the reporting method in this case, a method similar to oneof the aforementioned first to third exemplary embodiments can be used.

BM-SC 100 then reports, to RNCs 400-1 and 400-2, information of setvalues of radio resources of S-CCPCH and timing for transmitting theMBMS data in cells 600 under control thereof of the MBSFN informationthrough a different message. As the reporting method in this case, it ispossible to use one of a method of reporting set values themselves as inthe case of the aforementioned first exemplary embodiment and a methodof reporting MBSFN-Indicator indicating a combination of set values asin the case of the aforementioned second and third exemplaryembodiments.

Thus, the present exemplary embodiment can also form wide-range MBSFNcluster 700 extending over RNCs 400-1 and 400-2.

(5) Fifth Exemplary Embodiment (5-1) Configuration of Fifth ExemplaryEmbodiment

An overall configuration of a mobile communication system of the presentexemplary embodiment is similar to that in FIG. 3.

Furthermore, configurations of BM-SC 100, GGSN 200, SGSN 300, and RNCs400-1 and 400-2 of the present exemplary embodiment are also similar tothose in FIG. 10.

(5-2) Operation of Fifth Exemplary Embodiment

In the present exemplary embodiment, when starting a session of MBMS,BM-SC 100 negotiates with RNCs 400-1 and 400-2 under control thereof anddetermines radio resources of S-CCPCH and timing for transmitting MBMSdata in cell 600 under control thereof.

Storage unit 404 of RNCs 400-1 and 400-2 stores a database as shown inFIG. 18 that associates MBSFN-Indicator with a combination of radioresources and transmission timing set values beforehand.

When conducting the above negotiation, communication unit 102 of BM-SC100 transmits a message including MBSFN-Indicator which is a candidateto be used of MBSFN-Indicator to RNCs 400-1 and 400-2 first.

Upon receiving the message, control unit 402 of RNCs 400-1 and 400-2determines an MBSFN-Indicator available to control unit 402 itself andtransmits a message including the available MBSFN-Indicator tocommunication unit 403 to BM-SC 100.

Control unit 101 of BM-SC 100 selects one MBSFN-Indicator based on theavailable MBSFN-Indicator from each of RNCs 400-1 and 400-2. As acriterion in this case, an MBSFN-Indicator available to more RNCs may beselected, but the reference is not particularly limited to this.

Hereinafter, at the start of a session of MBMS, processing will becarried out according to the C-plane sequence chart in FIG. 5 using amethod similar to that in the aforementioned third exemplary embodiment.Thus, the MBSFN-Indicator value selected above is reported from BM-SC100 to RNCs 400-1 and 400-2 and MBSFN cluster 700 is formed.

Thus, the present exemplary embodiment can also form wide-range MBSFNcluster 700 extending over RNCs 400-1 and 400-2.

In the present exemplary embodiment, BM-SC 100 negotiates with RNCs400-1 and 400-2, but GGSN 200 or SGSN 300 may also negotiate with RNCs400-1 and 400-2. In this case, GGSN 200 or SGSN 300 serves as the corenetwork node, selects an MBSFN-Indicator and adds the MBSFN-Indicator toan MBMS Session Start Request message.

(6) Sixth Exemplary Embodiment (6-1) Configuration of Sixth ExemplaryEmbodiment

The present exemplary embodiment reports MBSFN information that has beenreported to one RNC to another RNC via an Iur interface. This can savethe resources of the Iu interface between SGSN and RNCs.

As shown in FIG. 19, an overall configuration of the mobilecommunication system of the present exemplary embodiment is differentfrom that in FIG. 3 in the following points. FIG. 19 shows three RNCs400-1˜400-3 as RNC 400.

That is, in the mobile communication system of the present exemplaryembodiment, only RNC 400-1 of RNCs 400-1˜400-3 under the control of SGSN300 receives MBSFN information reported from SGSN 300 via Iu interface410-3. Furthermore, RNC 400-1 and RNC 400-2 are connected via Iurinterface 410-1 and RNC 400-1 and RNC 400-3 are connected via Iurinterface 410-2. Though not shown in the figure, RNC 400-2 and RNC 400-3are connected to SGSN 300 via an Iu interface.

Furthermore, as shown in FIG. 20, when compared to FIG. 10,communication unit 403 of RNC 400-1 is further configured totransmit/receive messages and MBMS data to/from another RNC 400 underthe control of the same BM-SC 100.

On the other hand, when compared to FIG. 10, communication unit 403 ofRNC 400-2 is configured to transmit/receive messages and MBMS datato/from only another RNC 400 under the control of the same BM-SC 100 andnot to directly transmit/receive messages and MBMS data to/from SGSN300. The same applies to RNC 400-3, too.

(6-2) Operation of Sixth Exemplary Embodiment

Since a C-plane sequence chart of the mobile communication system of thepresent exemplary embodiment at the start of a session of MBMS issimilar to that in FIG. 5, descriptions thereof will be omitted.

However, in the aforementioned first to fifth exemplary embodiments,communication unit 102 of BM-SC 100 transmits a Session Start Requestmessage to all RNCs 400-1˜400-3 under control thereof, whereas in thepresent exemplary embodiment, communication unit 102 transmits a SessionStart Request message to only one RNC 400 (RNC 400-1 in FIG. 19) undercontrol thereof.

Avoiding transmission of a Session Start Request message to all RNCs400-1˜400-3 can save the resources of the Iu interface between SGSN 300,and RNCs 400-2 and 400-3.

In this case, communication unit 102 of BM-SC 100 can report MBSFNinformation to RNC 400-1 through the Session Start Request message usinga method similar to that in the aforementioned first to third exemplaryembodiments.

In this case, communication unit 403 of RNC 400-1 transfers the SessionStart Request to another RNC 400 under the control of same BM-SC 100 towhich MBMS data is to be transmitted (RNC 400-2, 400-3 in FIG. 19) viaIur interfaces 410-1 and 410-2 respectively.

Alternatively, communication unit 102 of BM-SC 100 can report MBSFNinformation to RNC 400-1 through the Session Start Request message andanother message, using a method similar to that in the aforementionedfourth exemplary embodiment.

In this case, communication unit 403 of RNC 400-1 transfers the SessionStart Request message and another message to another RNC 400 under thecontrol of same BM-SC 100 to which MBMS data is to be transmitted (RNC400-2, 400-3 in FIG. 19) via Iur interfaces 410-1 and 410-2respectively.

Thus, RNC 400-1 directly receives an instruction on the MBSFNinformation from BM-SC 100, whereas RNCs 400-2 and 400-3 indirectlyreceive the instruction on the MBSFN information from BM-SC 100 via RNC400-1.

RNCs 400-1˜400-3 instruct setting of radio resources of S-CCPCH in cell600 under their control and transmit MBMS data based on the MBSFNinformation directly or indirectly received from BM-SC 100.

Thus, the present exemplary embodiment can also form wide-range MBSFNcluster 700 extending over RNCs 400-1˜400-3.

When the present exemplary embodiment adopts a configuration ofreporting an MBSFN-Indicator to RNC 400-1 using a method similar to thatof the third exemplary embodiment, BM-SC 100, GGSN 200 or SGSN 300 maynegotiate with RNCs 400-1˜400-3 over the MBSFN-Indicator as in the caseof the fifth exemplary embodiment.

(7) Seventh Exemplary Embodiment

(7-1) Configuration of seventh exemplary embodiment

A mobile communication system of the present exemplary embodiment is anexample of case where the present invention is applied to a network ofevolved HSPA (High Speed Packet Access) or a network of LTE (Long TermEvolution).

These networks can assume a Flat Architecture configuration with an RNCdegenerated into a Node B.

As shown in FIG. 21, the mobile communication system of the presentexemplary embodiment includes BM-SC 100 and Node B 500.

FIG. 21 omits nodes (GGSN and SGSN) between BM-SC 100 and Node B 500 andillustrates a configuration applicable to both networks of evolved HSPAand LTE.

Furthermore, FIG. 21 illustrates three Nodes B 500-1˜500-3 as Nodes B500 and these Nodes B 500-1˜500-3 are connected to a CN (not shown)including BM-SC 100.

As shown in FIG. 22, the configuration of BM-SC 100 is similar to thatin FIG. 4 or FIG. 10.

Node B 500-1 includes time synchronization unit 501, control unit 502,communication unit 503 and storage unit 504. Nodes B 500-2 and 500-3also have a configuration similar to that of Node B 500-1.

The present exemplary embodiment corresponds to the first to fifthexemplary embodiments modified to a configuration supporting a FlatArchitecture and applies, to Node B 500, a method similar to the abovedescribed first to fifth exemplary embodiments applied to RNC 400.

Thus, Node B 500-1 is instructed with regard to MBSFN information fromBM-SC 100 as in the case of the aforementioned first to fifth exemplaryembodiments.

Furthermore, Node B 500-1 is instructed, as the information on setvalues of radio resources and transmission timing in cell 600 undercontrol thereof among MBSFN information, set values themselves as in thecase of the aforementioned first exemplary embodiment or anMBSFN-Indicator indicating a combination of set values as in the case ofthe aforementioned second and third exemplary embodiments.

Time synchronization unit 501 receives time information on UTC from GPSsatellite 900 and synchronizes time of Node B 500-1 with UTC.

In this case, Nodes B 500-2 and 500-3 likewise establish timesynchronization with UTC as well.

This allows time synchronization to be established between Nodes B500-1˜500-3.

The method of establishing time synchronization between Nodes B500-1˜500-3 is not limited to the aforementioned method by GPS, but themethod described in FIG. 4 may also be used.

Control unit 502 controls Node B 500-1 as a whole and performs varioustypes of operation. For example, in the present exemplary embodiment,control unit 502 sets the set values of radio resources designated byBM-SC 100 in S-CCPCH.

In this case, Nodes B 500-2 and 500-3 likewise set the set values ofradio resources designated by BM-SC 100 in S-CCPCH as well.

This allows all cells 600 under the control of Nodes B 500-1˜500-3 touse the same radio resource for S-CCPCH.

Communication unit 503 transmits/receives messages and MBMS data to/fromBM-SC 100. For example, in the present exemplary embodiment,communication unit 503 transmits MBMS data at the transmission timingdesignated by BM-SC 100.

In this case, Nodes B 500-2 and 500-3 likewise transmit MBMS data at thetransmission timing designated by BM-SC 100.

Time synchronization is established between Nodes B 500-1˜500-3.

This allows all cells 600 under the control of Nodes B 500-1˜500-3 totransmit the same MBMS data at the same transmission timing.

Thus, all cells 600 under the control of Nodes B 500-1˜500-3 cantransmit the same MBMS data using the same frequency and at the sametransmission timing, and can thereby form wide-range MBSFN cluster 700extending over Node B 500-1˜500-3.

(7-2) Operation of Seventh Exemplary Embodiment

The present exemplary embodiment also applies, to Node B 500, a methodsimilar to those of the aforementioned first to sixth exemplaryembodiments applied to RNC 400, and therefore descriptions of operationsthereof will be omitted.

The present exemplary embodiment can also form wide-range MBSFN cluster700 extending over Nodes B 500-1˜500-3.

(8) Eighth Exemplary Embodiment (8-1) Configuration of Eighth ExemplaryEmbodiment

The present exemplary embodiment reports MBSFN information that has beenreported to one Node B to another Node B via an interface. This allowsresources of the interface between the BM-SC and Node B to be saved.

As shown in FIG. 23, the mobile communication system of the presentexemplary embodiment is different from that in FIG. 21 in that only NodeB 500-1 of Nodes B 500-1˜500-3 under the control of BM-SC 100 receives areport about MBSFN information from BM-SC 100 and in that Nodes B500-1˜500-3 are connected via an interface. The interface between NodesB 500-1˜500-3 is an X2 interface in the case of an LTE network, forexample. Though not shown in the figure, Nodes B 500-2 and RNC 500-3 areconnected to BM-SC 100 via an interface.

Furthermore, as shown in FIG. 24, communication unit 503 of Node B500-1, compared to that in FIG. 22, is further configured totransmit/receive messages and MBMS data to/from another Node B 500.

On the other hand, communication unit 503 of Node B 500-2, compared tothat in FIG. 22, is configured only to transmit/receive messages andMBMS data to/from another Node B 500 and not to directlytransmit/receive these messages and MBMS data to/from BM-SC 100. Thesame applies to Node B 500-3, too.

(8-2) Operation of Eighth Exemplary Embodiment

Since the present exemplary embodiment results from modifying theaforementioned sixth exemplary embodiment so as to support a FlatArchitecture and from applying, to Node B 500 a, a method similar tothat in the sixth exemplary embodiment applied to RNC 400, descriptionsof operation thereof will be omitted.

In the present exemplary embodiment, BM-SC 100 can directly orindirectly instruct Nodes B 500-1˜500-3 with respect to MBSFNinformation, and can thereby form wide-range MBSFN cluster 700 extendingover Nodes B 500-1˜500-3.

The present invention has been described with reference to the exemplaryembodiments so far, but the present invention is not limited to theabove described exemplary embodiments.

The configuration and details of the present invention can be changed invarious ways in a manner understandable to those skilled in the artwithout departing from the scope of the present invention.

For example, in the aforementioned first to eighth exemplaryembodiments, BM-SC 100 instructs RNC 400 or Node B 500 with respect toparameters such as radio resources (frequency, scrambling code,channelisation code, slot format) and transmission timing as MBSFNinformation, but when the present invention is applied to an LTEnetwork, other parameters may be instructed instead of these parametersor other parameters may be additionally instructed. When, for example,OFDMA (Orthogonal Frequency Division Multiple Access) is used on adownlink, radio resources can be indicated by one of the following threepatterns. Since these patterns are not essential parts of the presentinvention, detailed descriptions thereof will be omitted.

(Pattern 1)

-   -   Subcarrier numbers and symbol numbers for allocating MBMS data        are instructed.

(Pattern 2)

-   -   MBMS data allocation time and frequency are additionally        instructed.

(Pattern 3)

-   -   Resource block numbers are instructed.

The method executed by BM-SC 100, RNC 400 and Node B 500 of the presentinvention may also be applied to a program to be executed by a computer.Furthermore, the program may also be stored in a storage medium and mayalso be delivered to the outside via a network.

The present application claims a priority based on Japanese PatentApplication No. 2008-281441, filed on Oct. 31, 2008, the disclosure ofwhich is incorporated herein by reference in its entirety.

1. A mobile communication system comprising: a mobile station; a basestation adapted to transmit Multimedia Broadcast Multicast Service(MBMS) data to the mobile station; and a core network node adapted totransmit, to the base station, an MBMS session start request messagethat includes a time to MBMS data transfer and a time of MBMS datatransfer which denotes a time of a start of the MBMS data transfer,wherein the base station is configured to: receive the MBMS sessionstart request message including the time to MBMS data transfer and thetime of MBMS data transfer; and take the time of MBMS data transfer intoaccount for the synchronization of a procedure related to a multicastcontrol channel instead of the time to MBMS data transfer.
 2. The mobilecommunication system according to claim 1, wherein a radio resourcesetup is performed according to the time of MBMS data transfer.
 3. Themobile communication system according to claim 1, wherein a radioresource setup is performed according to the time of MBMS data transfer.4. The mobile communication system according to claim 1, wherein thebase station is configured to transmit the MBMS data to the mobilestation according to the time to MBMS data transfer.
 5. A base stationin a mobile communication system comprising a mobile station and a corenetwork node, the base station comprising at least one memory storinginstructions and at least one processor configured to execute theinstructions to: receive, from the core network node, a MultimediaBroadcast Multicast Service (MBMS) session start request message thatincludes a time to MBMS data transfer and a time of MBMS data transferwhich denotes a time of a start of the MBMS data transfer; and take thetime of MBMS data transfer into account for the synchronization of aprocedure related to a multicast control channel instead of the time toMBMS data transfer.
 6. The base station according to claim 5, wherein aradio resource setup is performed according to the time of MBMS datatransfer.
 7. The base station according to claim 5, wherein a radioresource setup is performed according to the time of MBMS data transfer.8. The base station according to claim 5, wherein the at least oneprocessor is further configured to execute the instructions to transmitthe MBMS data to the mobile station according to the time to MBMS datatransfer.
 9. A core network node in a mobile communication systemcomprising a mobile station and a base station; the core network nodecomprising at least one memory storing instructions and at least oneprocessor configured to execute the instructions to: transmit, to thebase station, a Multimedia Broadcast Multicast Service (MBMS) sessionstart request message that includes a time to MBMS data transfer and atime of MBMS data transfer which denotes a time of a start of the MBMSdata transfer, wherein the base station is configured to: receive theMBMS session start request message including the time to MBMS datatransfer and the time of MBMS data transfer; and take the time of MBMSdata transfer into account for the synchronization of a procedurerelated to a multicast control channel instead of the time to MBMS datatransfer.
 10. The core network node according to claim 9, wherein aradio resource setup is performed according to the time of MBMS datatransfer.
 11. The core network node according to claim 9, wherein aradio resource setup is performed according to the time of MBMS datatransfer.
 12. The core network node according to claim 9, wherein thebase station is configured to transmit the MBMS data to the mobilestation according to the time to MBMS data transfer.
 13. A mobilestation in a mobile communication system comprising a base station and acore network node, the mobile station comprising at least one memorystoring instructions and at least one processor configured to executethe instructions to: receive Multimedia Broadcast Multicast Service(MBMS) data from the base station, wherein the MBMS data is based on atime to MBMS data transfer and a time of MBMS data transfer whichdenotes a time of a start of the MBMS data transfer, wherein the time toMBMS data transfer is different from the time of MBMS data transfer,wherein an MBMS session start request message, including the time toMBMS data transfer and the time of MBMS data transfer, is transmittedfrom the core network node to the base station, and the base station isconfigured to: receive the MBMS session start request message includingthe time to MBMS data transfer and the time of MBMSdata transfer; andtake the time of MBMS data transfer into account for the synchronizationof a procedure related to a multicast control channel instead of thetime to MBMS data transfer.
 14. The mobile station according to claim13, wherein a radio resource setup is performed according to the time ofMBMS data transfer.
 15. The mobile station according to claim 13,wherein a radio resource setup is performed according to the time ofMBMS data transfer.
 16. The mobile station according to claim 13,wherein the base station is configured to transmit the MBMS data to themobile station according to the time to MBMS data transfer.